The present invention relates to power tools and, more particularly, to reversible drill-type tools, such as portable electric drills.
Typically, electric drills, particularly of the hand-held type, are equipped with a chuck which may be loosened or tightened by the user of a chuck key which, for this purpose, is inserted into an aperture of the chuck and is turned to loosen or tighten elements of the chuck which clampingly engage the periphery of a drill shank or other shanked work piece or tool, such as the spindle of a polishing or sanding disk.
Since chucks of this type are most frequently employed for holding a drill, they are often referred to as drill chucks even though many other usages are made.
It is often inconvenient and bothersome to find the chuck key and insert the same in the chuck for tightening or loosening purposes. Often, the key is lost or misplaced and time which otherwise could be usefully spent is instead wasted hunting for the key. For this reason, various hand drill manufacturers have provided arrangements for retaining the chuck key by clipping it to the body of the drill, to the power cord for the drill, or attaching the key by means of a flexible cord of cable so that it cannot be lost.
Nevertheless, even if kept with the drill, the chuck key must be inserted within the chuck and manually manipulated in an awkward, slow and bothersome fashion in order to tighten or loosen the chuck for respective engagement or disengagement of the shank of the drill or other tool to be held by the chuck.
In recent years, electric hand drills of the type for which the invention is intended are often available with reversing features for permitting the chuck to be turned in either direction by the drill motor and also permitting the speed of the chuck to be varied by controlling the degree of energization of the electric motor. The present invention is intended to take advantage of the fact that, with such drills, tightening or loosening of the chuck can be obtained by holding the barrel of the chuck stationary while other elements of the chuck are turned in one direction or the other by operation of the drill at reduced power.
Accordingly, it is an object of the present invention to provide an accessory for facilitating engagement and disengagement of the shank of a drill or the like by a drill chuck, hereinafter referred to as a chuck.
A further object of the invention is the provision of such an accuracy which is readily attached to hand drills of typical commercially available design without requiring expensive or typical modification thereof.
Yet another object of the invention is the provision of such an accessory which utilizes the existing rotational operation of the drill in selective opposite directions to tighten or loosen the chuck for thereby facilitating engagement and disengagement of the shank of a drill or the like by the chuck.
A still further object of the invention is the provision of such an accessory which is selectively operable to effectively lock the chuck barrel to prevent it from turning relative to the drill housing whereby, on operation of the drill, the chuck will be selectively tightened or loosened.
A still further object of the invention is the provision of such an accessory which conduces to extremely convenient selective locking of the chuck barrel in a facile physiologically natural manner by the user.
Another object of the invention is the provision of such an accessory which can function in a manner to prevent damage to the drill in the event that excessive torque should be applied to the chuck by the drill motor when the chuck barrel is locked by use of the accessory.
Among still other objects of the invention may be noted the provision of such an accessory which is not only of relatively low cost construction but is simply and easily assembled, which is reliable and longlasting in operation, and which does not interfere with normal utilization of the drill.
Further objects will be in part apparent and in part pointed out hereinbelow.